The 26-year-old expectant mom told fans in an Instagram post on Thursday that she's pregnant and expecting a second daughter with husband Dakota Meyer.
"Dakota and Tripp officially outnumbered," she captioned a photo of herself and Meyer. "So excited to let you all know, ITS A GIRL!!"
Palin shares 14-month-old daughter Sailor Grace with Meyer, and is also mom to 8-year-old son Tripp Easton with ex-fiance Levi Johnston.
She said in a blog post in December that the new baby will complete her dream family of five.
"We are so excited about our expanding family!" Palin wrote. "Looking back many months ago, I would have never dreamed this is where I would be."
"Keeping with our unconventional life, it has been so much fun to keep this new just among our family and friends for the first half of our pregnancy," she added. "I always knew a third child someday would complete our family."
Palin, the eldest daughter of former Alaska governor Sarah Palin, married Meyer in June.
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